Definition of Hypothyroidism, infantile

Hypothyroidism, infantile: Underactivity of the thyroid gland that starts after birth in infancy or early childhood, as manifested by delays in growth and development, and by myxedema (a dry, waxy type of swelling, often including swollen lips and nose). Treatment involves use of thyroid hormone medication. Also known as Brissaud infantilism and infantile myxedema.